Silicon carbide as a substrate is an excellent material for power devices due to its wideband gap and high blocking voltage. However, dopants do not readily diffuse in silicon carbide substrate. Typically, dopants have been implanted into a silicon carbide substrate to form lightly doped base regions and heavily doped source regions by using two separate masks.
An example of this typical technique is disclosed in U.S. Pat. No. 5,338,945 (the"'945 Patent"). In the summary of the invention, the '945 Patent discloses "the base region of the silicon carbide field effect transistor is formed by amorphizing a first portion of a silicon carbide substrate, providing an implant of the base region dopant ions into the first portion and then recrystallizing the first portion to thereby create a substantially monocrystalline base region." The '945 Patent further discloses "Next, the source region is formed by amorphizing a second portion of the substantially monocrystalline base region, providing an implant of the source region dopant ions and then recrystallizing the second portion to thereby create a substantially monocrystalline source region in the base region." In other words, implanting dopants into a silicon carbide substrate has required at least two separate masks. The two mask technique is costly because two masks are used instead of one. More importantly, the two mask technique is difficult to use because the two masks must be properly aligned.